private static void ValidateHoleClockness(List <IntVector2> points)
{
var a = PolygonOperations.Punch()
.Include(new Polygon2(points))
.Execute();
Trace.Assert(a.Childs.Count == 1);
}
public static PolyTree ExtrudePolygon(IReadOnlyList <IntVector2> points, int offset)
{
if (points.Count <= 1)
{
throw new NotImplementedException("Not implemented: extrude 0 or 1 points");
}
if (offset <= 0)
{
throw new ArgumentOutOfRangeException();
}
List <IntVector2> polygonPoints = new List <IntVector2>(points);
// hack: fidget the last point slightly to enforce having area
var last = points[points.Count - 1];
var secondToLast = points[points.Count - 2];
var secondToLastToLast = secondToLast.To(last);
if (secondToLastToLast == IntVector2.Zero)
{
polygonPoints.Add(last + new IntVector2(1, 0));
}
else if (secondToLastToLast.X == 0)
{
polygonPoints.Add(last + new IntVector2(1, 0));
}
else
{
polygonPoints.Add(last + new IntVector2(0, 1));
}
for (int i = points.Count - 2; i >= 0; i--)
{
polygonPoints.Add(points[i]);
}
var inputHairlinePolygon = new Polygon2(polygonPoints);
var outputPolygons = PolygonOperations.Offset()
.Include(inputHairlinePolygon)
.Dilate(offset)
.Execute();
return(outputPolygons);
}